1. Field of Invention
The present application relates to a communication device and an antenna structure thereof. More particularly, the present application relates to a portable communication device and an adjustable antenna thereof.
2. Description of Related Art
With the rapid development of wireless communication technology, all kinds of portable communication devices are developed and widespread in daily life, such as mobile phones, personal digital assistants (PDA) and tablets. These portable communication devices have become an essential part of modern society.
The antenna component, configured for broadcasting/receiving radio waves and transmitting/exchanging radio data, is one of the most important components within the portable communication device in no doubts. Due to a variety of communication systems and their applications are introduced in recent years, the antenna is required to be designed for multiple bands, so as to cover multiple transmission frequency bands by the same antenna. In addition, because the appearance of the portable communication device tends to be compact, light-weighted and miniaturized, the antenna design is subject to the restrictions on the structural size, and it may increase the difficulties in designing the multi-frequency antenna.
The structure of Planar Inverted-F Antenna (PIFA) is commonly adopted by the portable communication device to implement a multi-frequency antenna, which is complied with requirements (e.g., light-weighted, compact-sized) on the portable communication devices. However, the multi-frequency antenna will be limited by the spacing distances between the antenna body, the ground and the metal frame, and it may further increase the difficulties in designing the multi-frequency antenna.
In addition, different wireless signals utilized by different applications (e.g., voice communication, wireless network, radio broadcasting, digital television, near-field communication) usually have different frequency bands on their own. It is difficult to implement multiple antennas or multiple antenna transceiver terminals corresponding to the individual different bands within the limited space of the portable communication device. Besides, a traditional antenna is hard to dynamically adjust the operating frequency bands since of the fixed characteristics of the antenna itself for the specific bands and the purpose after the assembly.
Some conventional designs provide antenna architectures with adjustable transceiver frequency. However, the adjustable antenna architectures in conventional designs require extra wirings in order to transmit control signals (used for adjusting frequencies) from the substrate to the antenna body or the adjusting units (e.g., switching components, variable capacitors) on the antenna carrier. It is noted that, each switching component requires a pair of wirings for control signals (e.g., one for the input signal and the other for the output signal) for controlling its operating states. The more different operating states required the more wirings for control signals are needed. However, additional wirings and elements may cause the antenna architectures even become more complex, and may also result in additional signal transmission noise.